You could defferentiated them by melting point but it might be difficult
because Test E. melts at 36-37.5 degC and Nandrolone Dec. melts at 32-35 degC
You could take a little (few mg) of each powder, place each pile on a metal plate (ie Alluminum plate) and heat them up very slowly with the heat of your hand or a light bulb generating little heat.
nandrolone should melt before Test. E.
Usually You would use a melting point apparatus. There pretty accurate and you could determine the melting point very easily. Unfortunetly they cost about 1000$.
One thing you should know is that if your powder is not pure (ie: has been cut)
the melting points will be way off.
As for smells touch etc, I see nothing in the chemical literature that would be helpfull
Hope this helps